An object to be handled in a product assembly line or delivered in an conveyed object delivery site is often conveyed on a conveyer line. In a delivery site, for example, a large number of conveyer lines are equipped lengthwise and crosswise. A transfer device is disposed at each of the cross points of the conveyer lines. The transfer device has a function of transferring an conveyed object from an original conveyer line (main conveyer line) to a different conveyer line (sub conveyer line) for transfer of the conveyed object to a desired position.
The transfer device includes two conveyer units for conveying an conveyed object, and a lifting and lowering unit for changing a height position of the conveyer units to perform the foregoing function. Each of the two conveyer units includes a conveying passage on which an object is placed and conveyed. The conveying directions of the conveying passages of the two conveyer units differ from each other. According to this transfer device, relative heights of the two conveying passages are switchable by using the foregoing lifting and lowering unit.
The lifting and lowering unit of the transfer device of this type retracts a top surface of the conveying passage of the conveyer unit not contributing to conveyance to a position below a conveying surface of the conveyer line, and lifts a top surface of the conveyer unit contributing to conveyance to the conveying surface side of the conveyer line to expose this surface. In this condition, the conveyer unit lifted to the conveying surface side operates (travels) to allow smooth conveyance without obstruction by the conveying unit not contributing to conveyance.
The transfer device further includes a regulating unit which allows upward and downward movement of each of the two conveyer units in a straight line.
In general, the regulating unit is a linear guide constituted by an erect pin or shaft, and a bearing member which slides the pin by engagement therewith.
For example, Patent Document 1 discloses a technology of the transfer device of this type.
In addition, Patent Document 2 discloses a multistage conveyer system which conveys objects on multiple conveyer devices overlapped with each other in the up-down direction.